Pressure-time responsive electronic firing device



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PRESSURE-TIME RESPONSIVE ELECTRONIC FIRING DEVICE Filed Dec. so, 1949 4sheets-sheet? FIG.2.

me/whom J. F. KEITHLEY M.L. SANDS 272mg M July 17, 1962 J. F. KEITHLEYETAL 3,044,398

PRESSURE-TIME RESPONSIVE ELECTRONIC FIRINC DEVICE Filed DCC. 50, 1949 4Sheets-Sheet 3 FIG. 3.

SWW/Mou J. F. KEITHLEY M. L. SANDS July 17`, 1962 .1. F. KEITHLEY ETAL3,044,398

PEEssUREJrIME RESPONSIVE ELECTRONIC FIRING DEVICE Filed Dec. 50, 1949 4Sheets-Sheet 4 ,l jfall" wl '53 I min-m2 1 I Y I 'L gmc/Maw J. F.KEITHLEY M. L. SANDS @www with iluid actuating means.

*Unitedl States vlate'nt C) 3,044,398 PRESSURE-TIME RESPONSIVEELECTRONIC FIRING DEVICE Joseph F. Keithley, 920 Keystone Drive,Cleveland Heights, Ohio, and Matthew L. Sands, 11 Westgate Cambridge,Mass. Y Y Filed Dec. 30, 1949, Ser. No. 136,132

' 14 Claims. (Cl. 102-18) (Granted under Title 35, U.S. Code (1952),sec. 266) This invention relates to a pressure responsive device whichis selectively responsive to a predetermined code of pressures by meansof a time delay systemV cooperating Provision is made in this inventionfor accelerating the desired response when the pressure impulsesreceived by the pressure responsive device are of such magnitude thatrapid reaction of the device is desirable.

In accordance with this invention in 4its preferred form, a plurality ofpressure operated mechanisms respond individually to predeterminedpressure changes in a conducting uid medium to operate their respectiveelectrical switches, thereby to cause an electrical system to integratethese varied responses until a certain predetermined controllingsummation has been reached. This ultimate summation may then be utilizedto cause the performance of any desired operation. Y Y

As an example of the application of this invention in its preferredform, the ultimate summation is used to explode a marine mine by meansof a detonator which is connected to the electrical system.

A vessel cruising on a body of water causes the water under and near thevesselY to flow thereby producing a pressure change on the bedrof thebody of water in accordance with Bernoullis theorem which states, thatan increase in the rate of flow of a uid is accompanied by a reductionin the pressure thereof. Actual tests have shown that a positivepressure peak is formed in front of and under the bow of the movingvessel and that a negative pressure region is formed justaft of the bowto the stern. It has been discovered that the positive pressure peak islocalized at the bow while the negative pressure region extendsathwartships a distance of several beams and decreases in proportion tothe distance athwartship. The pressure changes caused by la vessel rareknown as the vessels signature and it is Vknown that the general patternof the signature in constant for `varying speeds. The magnitudes of thepressures, which form a vessels signature, vary inversely as the squareof the depth of water at which these pressures are received.

It, therefore, follows that a pressure responsive system will experiencethe maximum pressure changes when a vessel passes directly thereover.The preferred embodiment of the present invention is adapted todiscriminate between these maximum pressure changes and pressure changescaused by distant ships, tides, waves, winds, and shallow draft Vesselswhich do not have the predetermined minimum vessel signature.

It is an object of this invention to provide la new and improved meanswhich is responsive to a predetermined code of pressures.

Another object is the provision of a -new and improv means adapted toprepare an electrical circuit Vfor clos-V ing in response to a rstpredetermined change in pressure and adapted to close said electricalcircuit in response 3,044,39g Patented July l?, 1962Y ice to a secondpredetermined change in pressure of a predetermined magnitude 'and timeduration.

Another object of this invention is to provide accelerating means forreducing the time duration Vrequired to close said electrical circuitwhen said second pressure change is of relatively large magnitude.

Another object is the provision of means for restoring the circuit tothe normally unprepared condition in the event the second pressurechange does not exist in suflicient magnitude for the required timeduration.

Another object of the invention resides in the provision ofa new andimproved mine firing control system which is adapted to become armed fora predetermined interval in response to a iirst predetermined pressuresignal, and to be iired if a second predetermined signal is receivedduring the predetermined interval; and in which means are provided forrestoring the system to an initialror unarmed condition in the event thesecond signal is not received during the predetermined interval.

Another object of the invention is to provide a mine firing controlsystem of the type hereinabove disclosed in which the sensitivity of thesystem is automatically adjusted in accordance with the depth ofsubmergence of the mine.

Another object is to provide within a marine mine a new and improvedfluid circuitv adapted to respond to changes in the pressure fieldadjacent the mine.

A further object resides in the provision of new and improved means forsubstantially filtering out or nullifying the effects of tides and wavesupon the tiring mechanism of a pressure controlled marine mine.

An additional object lies in the provision of a new and improved minewhich will not be subject to discharge by mine sweeping apparatus andcountermining means.

A still further object lies in the provision of a new and improved minetiring control system wherein the system operates tov detonate andexplode the mine associated therewith in response to the movement of asurface vessel within the zone of destructivity of the mine.

Other objects and many of the attendant advantages of this inventionwill Vhe readily appreciated as the same becomes better understood byreference to the following detailed description whenconsidered with theaccompanying drawings wherein:

FIG. 1 is a graph showing the pressure field caused by a moving vessel;

FIG. 2 is a diagrammatic view of the complete electrical and pressuresystem of thepressure-time responsive electronic device of the instantinvention according to the preferred embodiment thereof;

FIG. 3 is a view in section of the pressure responsive apparatus of theinstant invention, the switches and operating bellows therefor beingshown in elevation;

FIG. 4 is a somewhat enlarged plan view of the switches and switchoperating bellows as viewed from the bottom in FIG. 3; and j FIG. 5 is asectional view of the switch operating bellows and switches taken online 5--5 of FIG. 4.

Referring now more in detail to the drawings in which like referencecharacters refer to like parts throughout, the graph in FIG. 1 showsclearly the pressure changes Vcaused at various positions along a bed ofwater having a depth of 40 feet by a 6200 ton vessel traveling at l0knots.

A positive pressure peak is evident at the bow and a nega.-r

tive pressure region is evident from aft of the bow to the stern. Seawaves have been recorded which have positive pressure magnitudes equalto a vessels positive pressure peak, but no waves have been recordedwhich have similar negative pressure regions of such long time durationas, for example, about 15 seconds as seen in FIG. 1. The preferredembodiment of the instant invention is specifically adapted to respondto pressure changes caused by vessels such as above described but may,of course, be modified to respond to various other conditions where aresponse to a different code of pressures is desired.

A pressure-time responsive electronic device for ring a mine is shown inFIG. 2 and FIG. 3 wherein a watertight mine casing 6 is shown having abellows member 8 located at one end of the casing and exposed to seapressure. Contained within bellows 8 is -a housing member having holes 9located in the walls thereof and having a plate 16 mounted therein todivide said housing into a base pressure chamber 4 and a pressure changereceiving chamber 7. The plate 16 has ya small pressure equalizing oricetherein allowing restricted fluid communication between chambers 4 and7.

On plate 16 in chamber 7 is mounted a calibrated depth compensatingbellows 49 which has a switch supporting disc 20 mounted thereon. On thedisc 20 are mounted the electrical switches A, B, C, D, E, F and G whichare part of the electrical circuit to be described later. These switchesmay be of any suitable type such as, for example, microswitches. Whenthe calibrated bellows 49 is cornpressed by sea pressure, which istransmitted to chamber 7 by way of holes 9 from bellows 8, the disc 20is moved nearer the plate 16. rllhe distance disc 20 moves depends onthe depth of water in which the mine is planted, thereby compensatingfor the reduction in amplitude of the vessels signature. A limitingscrew 21 and a cooperating stopping block 24 are provided to limit themovement of the disc 20 at very large depths. The bellows 50-54 arecalibrated and move the switch operating pins 60, 61, 62, 63 and 64,predetermined distances in accordance with the pressure changesaffecting them. In FIG. 2 wherein it is assumed that the pressure inchamber 4 has been equalized through orice 15 with the pressure inchamber 7, the bellows 50-54 are in their normal positions.

The switch operating bellows 50 normally rests on switch A holding itopen; but when the pressure in chamber 7 is increased by a positivepressure signal, the bellows 50 `is compressed, thereby exhausting airthrough vents 10 into chamber 4 and allowing the spring-biased switch Ato close. As switch A closes, the condenser 65 is charged from battery76, thereby placing the proper operating bias on the cathode of the coldcathode discharge tube or valve 75; and the RC circuit comprisingcondenser 65 and resistance 91 maintains this operating bias on thecathode of tube 75 for a predetermined time after switch A has opened.

A second electric gas discharge tube or valve 74 is electricallyconnected to switches B-G, and is caused to be opened a predeterminednumber of times bythe actuation of these switches. When the pressure inchamber 7 is decreased a predetermined amount, the bellows 51 isextended due to the greater pressure in chamber 4 which is incommunication with the inside ofbellows 51 through Vents 11. The pin 61upon moving away from plate 16 causes switches B and D to open andswitch C to close. Switch C is located between the battery 77 and thecontrol grid of the tube 74 and when closed causes tube 74 to lire. Asthe tube is fired, the charge transferring condenser 66 which isconnected to the anode of Vtube 74 and which is normally charged frombattery 77 through the current limiter resistance 97 and throughnormally closed switch D, discharges through the tube 74. An RC circuitwhich controls the time between successive firings of tube 74 comprisesthe condenser 66 and resistors 90, 92, 93 and 94 through which thecondenser is selectively charged trom battery 77. The bellows 52, 53 and54 having respective Vents 12, 13 and 14 and respective pins 62, 63 and64 are calibrated to progressively close their respective switches E, Fand G as the change in negative pressure becomes progressively greaterin magnitude. This arrangement accelerates the ring of tube 74 when apressure signal of known origin is received since switches E, F and Gprogressively remove resistances 92, 93 and 94 from the RC circuit,thereby allowing condenser 66 to charge more rapidly. When a suicientcharge has been placed in condenser 66, tube 74 lires a second time.

A charge collecting condenser 67, which is normally discharged throughresistances 95 and 96 sand closed switch B, collects Va charge frombattery 77 through closed switch C and resistors 95 and 96 andestablishes a potential on the control grid of tube 75. When tube 74tires the second time before the voltage on condenser 65 has fallenbelow the operating Kbias of tube 75, the voltages of the condenser 67and the cathode of tube 74 add to trigger tube 75 and cause current toow therethrough from the condenser 96. The current responsive device andcondenser 96 are connected in series with a current limiting resistance99 and battery 77 This arrangement allows condenser 96 to receive energyfrom the battery 77 at a low current which is insuicient to activate thecurrent responsive device 100. When the grid of tube 75 is properlybiased, however, the current from the condenser 96' passes through tube75 to the current responsive device which is arranged to cause theperformance of any desired operation.

Although a marine mine detonator 100 has been chosen as the preferredembodiment of a current responsive device, it will be understood thatthis invention is not limited to this arrangement since thepressure-time responsive electronic device may be used to operatevalves, gauges, and other current responsive devices which may bedesirable in a hydraulic or pneumatic system.

Also any pressure responsive means such as diaphragms and the like maybe used to transmit the changes in pressure to switch operating meanswithout departing from the scope of this invention.

In explanation of an application of the instant invention, let it beassumed that a marine -mine is planted in a bed of water having a knowndepth `of 40 feet. The water pressure at this depth is transmitted frombellows 8 through holes 9 to chamber 7 where it causes bellows 49to-draw disc 20 a predetermined distance toward plate 16. After apredetermined time of, for example, several hours, the pressures inchambers 4 and 7 are equalized through orifice 15 which places thepressure system of the mine in a readied condition to respond to apredetermined code of pressure signals.

Assume that a ship having the pressure signature shown in FIG. 1 passesdirectly over the mine thereby subjecting the instant invention to apositive pressure peak for about 5 seconds and a negative pressureregion for about l5 seconds. Upon receipt of the positive pressure peak,bellows 50 compresses allowing switch A to spring closed and completethe circuit for charging condenser 65, thereby placing the properoperating bias on the cathode of the firing tube 75 for a predeterminedtime duration such as, for example, 45 seconds following the opening ofswitch A. Immediately following, ,the bellows 51 expands due to thenegative pressure regionshown in FIG. 1, thereby opening switches B andD and closing switch C, which places the proper operating potential onthe grid of tube 74. The arming tube 74 res at this point, dischargingthe condenser 66 whereupon the tube is extinguished and the condenserbegins to recharge immediately causing tube 74 to re a second time at aninterval determined by the time constant of condenser 66 and resistances90, 92, 93 and 94 which maybe, for example, 15 seconds. The chargecollecting condenser 67 has, in the meantime, been charging throughclosed switch C and upon the second firing of the arming tube 74 willadd to the voltage at the cathode of tube 74 to elevate the potential onthe control grid of the tube 75 to a value sufficient to fire tube 75.On ring of the tube 75, the condenser 96 discharges through the tube 75and causes the detonator 100 to ignite, thereby exploding the mine.

It is necessary that the switch C be held closed for a predeterminedoptimum time of at least 15 seconds, for example, which is the assumednormal RC of the circuit for controlling re-ring or cycling of tube 74,in order to cause tube 75 to iire. Sea waves do not present a negativepressure cycle of sufficient duration to hold switch C closed for therequired predetermined optimum time. Therefore, switch C is opened andswitches B and D are closed by the succeeding positive pressure halfcycle of a wave. When switch B is closed, the condenser 67 is shortcircuited through resistances 95 and 96 thereby restoring the device tothe initial readied condition, i.e. placing the circuit` in readinessfor response to a negative pressure signal of proper amplitude-timefunction. By reason of this arrangement, if the circuit is armed by thepositive pressure of a wave, it cannot subsequently be red by a vesselmoving athwartship with respect to the mine as the succeeding positivepressure half cycles ofthe wave cause switch B to close. When switch Dis closed, condenser `66 is charged from battery 77 through resistance97.

Tides are compensated -for by the orifice 15 which permits pressureequalization in the chambers 4 and 7.

lf aship having a positive pressure peak followed by a negative pressureregion which is of great magnitude passes over the mine, it is notnecessary that a time interval of 15 seconds pass between the rst andsecond rings of tube 74 since such a pressure signature is peculiar tolarge vessels only. Therefore, an accelerating means is provided whichby means of bellows 52, 53

v and 54 cuts out the resistances E, F and G respectively in accordanceWith the progressively increased setting of the bellows. This reducesthe resistance in the RC circuit of tube 7-4, allowing the condenser 66to charge more rapidly, and ultimately tiring tube 74 more rapidly.Since condenser 67 charges quite rapidly on closing switch C, the tube75 is tired sooner also, thereby exploding the miner Obviously manymodifications and variations of the present invention are possible inthe light of the above teachings. It is therefore to be understood thatwithin the scope of the appended claims the inventionV may be practicedotherwise than as speciiically described.

The invention described herein'may be manufactured and used by or'forthe Government of the United States of America for governmental purposesWithout the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

l. A pressure-time responsive device operable in response to apredetermined code of pressures comprising means responsive to a firstpredetermined pressure for initially preparing said device foroperation, means. for causing the operation of said device in responseto a second predetermined pressure existing for a predetermined minimumtime interval, and means for reducing said predetermined minimum timeinterval when said second pressure is of relatively large magnitude.

2. A pressure-time responsive device operable in response to apredetermined `code of pressures comprising means responsive to a lirstpredetermined pressure for initially preparing said device foroperation, means for causing the operation of said device in response toa v second predetermined pressure existing for a predetermined minimumtime interval, means for reducing said predetermined minimum timeinterval when said second pressure is of relatively large magnitude, andmeans for returning said device to the initial prepared condition inresponse to the 'cessation of the second pressure before 'the expirationof the predetermined minimum time Vinterval.

3. A marine mine Atiring device operable to arm and fire a mine inresponse to a vessels pressure signature having 4.' A marine mine iiringdevice operable to arm and i tire a mine in response to a vesselspressure signature having a positive pressure peak and a negativepressure region, comprising, means responsive to a predeterminedpressure of the positive pressure peak for initially arming the mine,means for tiring the mine in response to the existence for apredetermined minimum time interval of a predetermined pressure of saidnegative pressure region, means for reducing the predetermined minimumtime interval in response to a pressure of said negative pressure regionof'relatively large magnitude, and means for returning said device tothe initial armed condition in response to the cessation of thepredetermined pressure of said negative pressure region before theexpiration of the predetermined minimum time interval.

5. In a pressure responsive device selectively responsive to apredetermined code of pressures for operating aV switchAcontrolledelectrical circuit comprising a housing having Va rst end portion and asecond end portion, said rst end portion having a plurality of holes inthe side walls thereof, a plate mounted in said housing having apressure equalizing oriiice and a plurality of vents therethrough, saidplate forming-a control chamber at said rst end portion and a basepressure chamber at said second end portion, a pressure responsivemember exposed to a pressure signal conducting medium and mounted onsaid ihousing in pressure communication with said control chamberthrough said plurality of holes, a plurality of graduated pressureresponsive switch operating members individual to said plurality ofvents and mounted in said control chamber on said plate in communicationwith said base pressure chamber through said Vvents, and a depthcompensating bellows mounted on said plate within said control chamberand having a plurality of switches mounted thereon in operative relationwith respect to said plurality of switch operating members.

6. A pressure-time responsive device operable in response to apredetermined code of pressures comprising trst means responsive to apredetermined positive pressure for placing said device in a preparedcondition for operation, Vsecond means responsive to a predeterminednegative pressure existing for a predetermined time inlterval forcausing said device to operate, means responsive to a change in pressurefrom nega-tive to positive prior to the passage of said time intervalfor returning said device to the prepared condition, and meansresponsive to negative pressure of relatively great magnitude .fforcausing said device to operate in less lthan said predetermined timeduration.

' 7. In a mine firing' device, the combination of detonating means, anda pressure responsive device adapted to re -said detonating means inresponse to Ithe pressure signature of a vessel, said device comprising,lirst means responsive to positive pressure resident in said signature`to initially arm said mine, second means responsive to negativepressure resident `in said signature and existing for a predeterminedtime interval to re said detonator, third means responsive to acessation of said negative pressure before the passage of saidpredetermined time interval to return said mine to said initially armedcondition, and fourth means responsive to'negative pressures ofrelatively large magnitudes resident in vsaid signature for causing saiddetonator to tire before the passage of said predetermined timeinterval.

8. A pressure-time responsive electronic device responsive .to apredetermined Vcode of pressures comprising power supply means; anelectric gas discharge device connected to said supply means and havingan anode, a cathode and grid; an R.C. circuit having a first condenserconnected to said cathode for maintaining the proper bias on saidcathode; first bellows actuated switch means responsive -torpositivepressure for connecting said R.C. circuit to said power supply means toplace a charge on said first condenser, a second condenser connected tosaid grid for .building up the voltage on said grid as the condenser ischarged, second bellows actuated switch means responsive to negativepressure for connecting said condenser to said power supply means, meansfor shortcircuiting said second condenser when said second switch meansis opened, third bel-lows actuated switch means responsive to negativepressure, means actuated by said )third means for supplying the properoperating bias to the grid :in additive relation to said voltage builtup thereon and including an R.C. circuit which delays such supply for apredetermined time period, and `fourth bellows actuated switch meansresponsive -to negative pressures of relatively large magnitudes lforreducing said predetermined time period-thereby causing said dischargedevice to fire more rapidly.

9. A pressure-time responsive electronic device responsive to apredetermined code ofA pressures comprising, power supply means, anelectric gas discharge device connected to said power means having ananode, a control grid, and a cathode; first means connected to saidcathode and said power means for conditioning said discharge device foroperation and comprising a switch, positive pressure actuated means forclosing said switch, and a first R.C. circuit for maintaining the properbias on said cathode for a predetermined time after said switch isopened; second means connected to said control grid and said power meansfor rendering said device conductive and comprising a condenser, asecond switch, negative pressure actuated means for closing -said secondswitch to charge said condenser, means for short circuit-ing saidcondenser when said second switch is open, means lfor adding voltagesufiicient to operate said electric discharge device to the voltage ofsaid condenser comprising a discharge tube, a second R.C. circuit havinga predetermined time constant controlling the firing of said tube, athird switch 4in the second R.C. circuit, negative pressure actuatedmeans for maintaining said third swi-tch closed, said second R.C.circuit having a plurality of resistors, a plurality of switch meansconnected to said resistors for short-circuiting their respectiveresistors, and a plurality of means actuated by negative pressures ofrelatively large magnitudes for successively closing said -switch meansas the large magnitude negative pressures increase.

10. A device of the character described responsive to a predeterminedcode of pressure signals comprising a condenser, means 4for chargingsaid condenser to a predetermined potential in response to apredetermined pressure signal, means connected to said condenserresponsive to a predetermined pressure signal existing for apredetermined time tfor providing an increased voltage at saidcondenser, and additional means operatively connected to said condenserfor providing said increased voltage at the condenser in less than saidpredetermined time in response to a relatively large pressure signal.

1l. A pressure responsive device selectively responsive to 4apredetermined code of pressures comprising, a source of current, anelectric gas discharge device connected to said source and having ananode, a cathode and grid, means responsive to positive pressure ofshort time duration to prepare said cathode for current conductingcondition for a predetermined time period, means connected to saidsource responsive to negative pressure of a predetermined minimummagnitude and minimum time duration for building up the potential onsaid grid to a value sufficient to fire said electric device within saidtime period, and means responsive to negative pressures of relativelylarge magnitude for accelerating the grid potential build-up thereby tocause said device to fire in less time than said predetermined minimumtime duration.

12. A pressure responsive device selectively responsive to a code ofpressures comprising, power source means; an electric gas discharge tubeconnected to said power source means and having an anode, a cathode anda grid; means responsive to positive pressure to connect said cathode tosaid power source means to prepare said cathode for current conductingcondition, said means including an R-C circuit having a predeterminedtime constant for maintaining said cathode in current conductingcondition for a predetermined period of time; means connected to saidpower source means and responsive to negative pressure of apredetermined minimum magnitude and minimum time period for building upthe potential on said grid to a value sufiicient to fire said electrictube; and means responsive to relatively large negative pressures forreducing the time period for building up the potential on said gridthereby to cause said tube to fire more rapidly.

13. In a control circuit of the character disclosed, the combination offirst and second cold cathode tubes each having anode, cathode andcontrol grid elements, first and second cathode load resistorsindividual to said tubes, first and second initially charged condensersconnected respectively across the series combinations of the maindischarge gaps of the tubes and the cathode load resistors individualthereto, the charge on each of said first and second condenser beingsufficient to render the tube individual thereto conducting when anoperating voltage corresponding to the control gap break down potentialthereof is applied between the control grid and cathode elements of thetube, a third condenser coupling the cathode element of the first tubeto the ygrid element of the second tube, a coupling resistorinterconnecting said control grid elements, a battery including a lowpotential section connected between said cathode load resistors so as tonegatively bias said second tube, a fourth condenser shunted across thecathode load resistor of the second tube, means for momentarily chargingsaid fourth condenser in a direction to counterbalance said negativebias on the second tube, a first switch means for applying saidoperating voltage from said battery across the control gap ot the firsttube through said third condenser when the switch means is operated froman initial position to a moved position thereby to render the first tubeconducting to discharge said first condenser therethrough andsimultaneously therewith to charge the third condenser from the batterywhereby the voltage across the control gap of the second tube iselevated by the voltage developed on the third condenser, said firstswitch means being constructed and arranged to discharge said thirdcondenser through said coupling resistor and the first load resistorwhen the first switch means is returned to said initial position, asecond switch means for recharging the first condenser from said batteryto a potential sufficient to render the first tube conducting a secondtime whereby the voltage developed across the first load resistor addsto the voltage developed on the third condenser sufiiciently to applysaid operating potential to the control gap of the second tube to renderthe second tube conducting, and an electroresponsive device arranged tobe operated by the energy discharged from the second condenser as thesecond tube is rendered conducting.

14. A pressure-time responsive electronic device responsive to apredetermined code of pressures comprising power supply means, a coldcathode discharge tube connected to said power means, first meansconnected to said tube for conditioning the tube for operation andcomprising a switch, positive pressure actuated means for closing saidswitch, an R.C. circuit for maintaining the proper bias on said tube fora predetermined period of time after said switch is opened, second meansconnected to said tube and power means for rendering said tubeconductive and comprising a condenser, a second switch,

negative pressure actuated means for closing said second switch tocharge said condenser, means for short circuit# in the second R.C.circuit, and means responsive to negative pressure for maintaining saidswitch means closed.

References Cited in the iile of this patent i UNITED STATES PATENTS2,388,459 Allen n Nov. 6. 1945

